OK, thanks for the prompting, I decided to take the plunge and try to make an m.2 SSD my OS/sims drive. Sounds like it could be a bit tricky, but maybe not so much with a fresh win 10 install.

All parts are now ordered!

I also changed course, to go with a ASUS Z-170 pro gaming mobo. (The m.2 research I did showed some potential trouble with the Gigabyte I was looking at. Plus, I've been happy with my current 5 year old Asus mobo.) I did my due diligence half-assedly, and while I made sure I was getting compatible RAM and SSD, I had already ordered a PSU I found an OK deal on ama$on for, a Corsair RM1000x (yes I know, overkill, but it was a good deal!), and it's not on Asus' list. Any opinions on how important that really is? I understand RAM is one thing, but it seems like a good PSU (and this one got great reviews) should work for any good mobo...

Or maybe I'll just go ahead and order the Golden Field ATX-S395(靜音版), that IS on their list

Thanks for all the input, guys, I really appreciate it. Of course for these questions I can (and did, and did...) google for answers, but you know that tends to produce too many contradictory and/or misinformed answers, so it's nice to have a group of friends to get fall-back opinions from, more the old fashioned way.

Like I said, parts are on the way, and should all be here within a week. Will let you know how the build goes!

After throwing out that statement, "PSU degrades with time" which was based on most of what I've read over the years, I wanted to back it up, but can't find anything solid to cite. Seems it might be one of those myths everyone clings to, but I won't give up yet. This is the best I could find, an article about capacitor aging, but well over my head: http://www.johansondielectrics.com/ceramic-capacitor-aging-made-simple#.Um_e0fmkr9k

Meanwhile some good advice:

The best advice is for someone to get a quality manufactured power supply that has been torture tested by Hardware Secrets, Johhy Guru, or HardOcp. These reviewers take apart the PSU and inspect the circuitry to ensure the claimed features are present. I don't know how many times I have seen them say "there is no over-volt circuit even though that is a claimed feature, avoid this power supply".